Conventional hoses which are used as conduits for hydraulic fluids generally have a maximum working pressure of less than 15,000 psi. This pressure limitation imposes severe restrictions on the design and configuration of certain types of equipment. For example, techniques such as swagging for the deformation of metal components often employ pressures in the 30,000 to 60,000 psi range.
Exemplary equipment of this type is used to expand metal tubes within the tube sheets of heat exchangers used as condensers in nuclear power plants. There may be more than a thousand such tubes extending through a single tube sheet and the task of expanding each tube is time consuming and labor intensive.
Conventionally, pressurized hydraulic fluid from a pump is supplied by a hose to a power head that is connected sequentially to a mandrel in each tube to be expanded. An intensifier is mounted on the power head to boost the pump pressure to the desired magnitude, using a combination of pistons of different diameters. The power head with the intensifier is a heavy and cumbersome piece of equipment that cannot be manipulated by one person without the aid of an elaborate support apparatus that restricts its freedom of movement significantly. If a flexible conduit were available, permitting universal movement at one end relative to the other and capable of withstanding pressures in the 30,000-60,000 psi range, it would be possible to mount the intensifier on the pump instead of the power head. Consequently, the head could be a much smaller, lighter and more compact tool that could be more quickly and easily manipulated.
It is believed that there are some circumstances in which rigid metal tube-like sections have been connected end-to-end with movable joints between them as a substitute for a hose. This type of construction is not always a suitable substitute, however, in circumstances in which the employment of a hose would impose undesirably low pressure limitations. The joints between the rigid sections are not capable of withstanding pressures sufficiently higher than those at which a hose could be used and often do not permit the desired freedom of movement. This pressure limitation dictates that such rigid section arrangements are not suitable for the tube and tube sheet application described above.
A principal objective of the present invention is to provide a high pressure fluid conduit that overcomes the above limitations of previously known devices.